This invention relates to a superheterodyne receiving circuit and a superheterodyne receiver.
A method is known wherein, in a receiving circuit or receiver of the superheterodyne type, a local oscillation frequency is adjusted so as to be equal to the frequency of a received signal to adjust an intermediate frequency to zero.
Where the method described above is employed, most components of a receiving circuit can be incorporated into a one-chip IC (integrated circuit) as hereinafter described, and consequently, reduction in size and weight, equalization in characteristic and reduction in cost of a receiver can be achieved.
However, with the receiving method described above, since the local oscillation frequency is equal to the frequency of the received signal, the local oscillation signal leaks from the local oscillation circuit via a mixer circuit to the antenna side to increase the level of undesired radiation.